Functional anatomy of the anophthalmic socket: insights from magnetic resonance imaging.

PURPOSE Changes in anophthalmic socket anatomy can significantly compromise esthetics and motility after enucleation. This study evaluated such changes by using magnetic resonance imaging (MRI) of enucleated and fellow orbits. METHODS High-resolution, surface coil MRI was performed in five patients after enucleation for uveal melanoma. Images were analyzed quantitatively to determine extraocular muscle (EOM) volume, maximum diameter, and length; orbital, optic nerve (ON), and orbital fat tissue (OFT) volume; and implant position. The fellow orbit was used as the control. Patients evaluated their satisfaction with the surgical results and were clinically examined. RESULTS Rectus EOM volume was slightly but not significantly reduced on the surgical compared with the control side. Oblique EOM and OFT volumes were unchanged. Rectus EOM length was significantly reduced in the surgical side, but maximum EOM diameter in central gaze position was slightly but not significantly greater on the enucleated side. Rectus EOM paths were not qualitatively changed by enucleation and continued to exhibit the influence of the connective tissue pulleys, which retained motility, as appropriate to EOM contraction. Implants were located significantly posterior to the normal globe location. CONCLUSIONS Enucleation does not significantly change EOM volume, but shortens EOM paths, a change that would be expected to alter their mechanical properties. EOM pulleys appear to retain their functional role in enucleated orbits.